What is a garden annexe?
A garden annexe is a single-storey building in the garden with its own living space, bathroom and often a kitchenette, used by relatives, older children or guests. Unlike a garden room, it is built as habitable accommodation with foundations, insulation and services.
How much does a garden annexe cost in Uxbridge?
In Uxbridge, a garden annexe typically costs £2,350–£3,650 per m² of floor area, including VAT at 20% (standard rate). For a typical 35 m² project that is roughly £82,000–£128,000. Building costs in London run about 30% above the UK average, and the figures for Uxbridge are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (24 m²) | £56,500–£87,500 |
| Typical project (35 m²) | £82,000–£128,000 |
| Larger project (49 m²) | £115,000–£179,000 |
| Rate per m² | £2,350–£3,650 |
What moves the price most:
- Cladding and finishes
- Heating type
- Kitchen and bathroom
- Size and layout
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a garden annexe in Uxbridge?
Approvals for a garden annexe in Uxbridge follow the rules for England. In England an annexe used as living accommodation usually needs planning permission. Outbuildings built under permitted development must be incidental to the house, such as a gym or office, not a bedroom.
Building regulations approval comes from the council’s building control service or a registered building control approver. The work is inspected at key stages, such as foundations, drainage and insulation, and a completion certificate is issued at the end.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
On a typical garden annexe we handle:
- External cladding or brickwork
- Kitchenette and shower room
- Insulated walls and roof
- Building control sign-off
- Planning drawings and application
- Electrics and heating
How long does it take?
The build itself usually takes 10 to 16 weeks on site. Before that, surveys, drawings and approvals usually take 3 to 4 months, longer if the council asks for changes.
Building in Uxbridge
Victorian and Edwardian terraces dominate many London streets, which is why side return, wraparound and mansard projects are so common here.
From UB8 outwards, we take on projects throughout Uxbridge and the surrounding parts of Greater London.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about garden annexes in Uxbridge
Does it need building regulations?
Yes, as it contains sleeping accommodation and services.
How much does a garden annexe cost in Uxbridge?
In Uxbridge, a garden annexe typically costs £2,350–£3,650 per m² of floor area, including VAT at 20% (standard rate). A typical 35 m² project comes to roughly £82,000–£128,000. Your fixed price depends on the survey and drawings.
Will council tax apply?
Annexes can be banded separately, though discounts or exemptions apply in some cases when occupied by family. Check with your council.
How long does it take?
Typically 10 to 16 weeks on site.
Do you build garden annexes in Uxbridge?
Yes. We build garden annexes across Uxbridge, including postcodes UB8. Every project starts with a free home visit.